The invention relates to the use of solid pigment preparations as colorants for coloring seed and seed-dressing materials.
Seed dressing constitutes a widely used form of treating plants with pesticides. Pesticides are understood as meaning, in particular, herbicides, insecticides, fungicides and other crop protection agents.
Nowadays, seed is treated with pesticides in seed-treatment plants in which the pesticides are usually in the form of a xe2x80x9cformulationxe2x80x9d when mixed with the seed. Suitable mixing methods are, for example, xe2x80x9cpelletingxe2x80x9d, granulation, or encrusting, during which process either preformulated seed dressing products are applied to the seed in the form of a coating or individual formulation components are applied immediately prior to or during the mixing process. The active ingredients (i.e., pesticides) are generally present in the seed-dressing formulations as solids which are employed, for example, in the form of their wettable powders or granules, aqueous suspensions or emulsions, or suspensions or emulsions that are miscible with water.
The seed-dressing formulations may additionally also contain inorganic or organic binders (for example, film-forming polymers that are miscible with water, surfactants, biocides, thickeners, protective colloids, or antifoams). Usually, however, they additionally contain a colorant, particularly an inorganic or organic color pigment. The purpose of such colorants is to mark or distinguish between certain types of seed by color, to protect the seed from feeding damage by birds, to improve the stability of the formulation formula, or else to serve as filler. The pigments are used either in the form of pigment powders or in the form of liquid, in general water-based, preparations.
The use of red aqueous pigment preparations is described in Examples 1 and 2 of WO-A 99/29169 and the use of inorganic iron oxide pigment powder is described in Example 2 of EP-A-1 3 769.
The colorants (pigments) can be added to preformulated seed-dressing products or added to the seed before or during the mixing process, together with the other formulation components. Customary pigment powders have the disadvantage that the pigment particles are still greatly aggregated or agglomerated, so that complete wetting and dispersion of the pigments during the mixing process is frequently unsuccessful. The great evolution of dust during handling is also disadvantageous.
While, in principle, aqueous (predispersed) pigment preparations permit a more intensive coloring, they lead to an undesired dilution of the seed-dressing products and are therefore suitable for industrial application only to a limited extent. Moreover, they are more complicated with regard to packaging and transport and require specific provision in order to be sufficiently storage-stable (preservation, prevention of drying out, antifreeze protection, and the like). Frequentlyxe2x80x94for example, in the case of C.I. Pigment Redxe2x80x94aqueous preparations of the prior art show a pronounced tendency to thickening and thus lack storage stability.
There is therefore a desire for new, readily dispersible highly concentrated pigment preparations that may be used in all seed-treatment product application methods and that overcome the disadvantages described above and are economical to produce. In particular, there is a need for pigment preparations in the hue ranges red, blue, green, and white.
Solid pigment preparations are already known in other fields of industrial application, such as, for example, for pigmenting building materials, renderings, and dispersion paints.
DE-A 19 523 204 and DE-A 2 608 993 describe pigment preparations in powder form, as well as processes for their preparation, that are characterized by the use of film formers or protective colloids that are very readily soluble in water (such as, for example, those based on polyvinyl alcohol/vinyl alcohol mixtures, vinyl alcohol copolymers, or polymers of N-vinylpyrrolidone) in addition to pigment and dispersant in order to ensure the good dispersability of the preparations in the aqueous media in which they are used. However, such film formers are undesirable in formulation formulas for seed-dressing materials since they have a thickening effect in the formulasxe2x80x94also as a result of the large quantity that is requiredxe2x80x94or may undergo other adverse interactions with seed-dressing product components.
Another disadvantage of solid, as well as liquid, pigment preparations comprising organic film formers or protective colloids is that they reflocculate in the aqueous media in which they are used in the course of prolonged mixing times, lose color intensity, and in most cases also change the hue. This applies very particularly to preparations based on copper phthalocyanine pigments and pigments based on laked colorants, which are already widely used in the field of seed-dressing materials in their powder form. Liquid pigment preparations that are based on laked colorants, such as, for example, Colour Index Pigment Red 48:2, and that have been produced in accordance with the prior art additionally have the disadvantage of lacking storage stability with regard to viscosity and coloristic.
There is therefore a need for readily redispersible pigment preparations having improved storage stability and high pigment content without the abovementioned disadvantages of solid pigment preparations of the prior art.
The invention therefore relates to a method comprising coloring (color pigmentation) seed, seed-dressing materials, or seed-dressing material formulations (preferably aqueous ones) with solid pigment preparations comprising
(a) at least one organic or inorganic pigment and
(b) at least one compound selected from the group consisting of polyether polyols, reaction products of alkylene oxides with alkylatable compounds (such as fatty alcohols, fatty amides, fatty acids, phenols, alkylphenols, carboxamides, and resin acids), or oxalkylated phenols (particularly phenol/styrene polyglycol ethers),
wherein the solid pigment preparations have a water content of less than 10% by weight (preferably less than 3% by weight), based on the pigment preparation, and a mean weight average particle size of 20 to 2000 xcexcm (preferably 50 to 1000 xcexcm and more preferably 80 to 500 xcexcm) and are preferably obtained without the addition of organic protective colloids or film formers.
The solid pigment preparations are preferably obtained in the form of readily flowable, low-dust granules by spray-drying methods.
The organic or inorganic pigments of component (a) are not subject to any limitation.
Examples of suitable pigments are those known from the prior art as can be seen, for example, in: Lxc3xcckert, Pigment+Fxc3xcllstoff Tabellen [Pigment+Filler Tables], 5th edition, Laatzen, 1994. These materials are insoluble in aqueous media.
Examples of suitable inorganic pigments are white and color pigments.
Inorganic white pigments that may be mentioned are, in particular, oxides such as, for example, titanium dioxide, zinc oxide (ZnO, zinc white), zirconium oxide; carbonates such as, for example, lead white; sulfates such as, for example, lead sulfate; and sulfides such as, for example, zinc sulfide, and lithopones. Titanium dioxide is especially preferred.
Inorganic color pigments that may be mentioned are pigments from the group of oxides and hydroxides as their inorganic individual compounds or as mixed phases, in particular iron oxide pigments, chromium oxide pigments, and oxidic mixed-phase pigments with rutile or spinel structure, and bismuth vanadate, cadmium, cerium sulfide, chromate, ultramarine, and iron blue pigments.
Example of iron oxide pigments are Colour Index Pigment Yellow 42, Pigment Red 101, Pigment Blue 11, Pigment Brown 6, and transparent iron oxide pigments.
Examples of chromium-oxide pigments are Colour Index Pigment Green 17 and Pigment Green 18.
Examples of oxidic mixed-phase pigments are nickel titanium and chromium titanium yellow, cobalt green and cobalt blue, zinc iron brown and chromium iron brown, and iron manganese black and spinel black. Iron oxide pigments, particularly red iron oxide pigments, are preferred.
Also preferred are carbon blacks, which are considered pigments for the purposes of the present application and of which a large number is known, for example, from Colour Index, 2nd edition. Carbon blacks that may be mentioned in particular are acidic and alkaline carbon blacks obtained by the furnace process and chemically surface-modified carbon blacks, for example sulfur- or carboxyl-containing carbon blacks.
Examples of preferred organic pigments are those of the monoazo, disazo, laked azo, xcex2-naphthol, napthol AS, benzimidazolone, disazo condensation, azo metal complex, isoindoline, and isoindolinone series, as well as polycyclic pigments such as, for example, from the phthalocyanine, quinacridone, perylene, perinone, thioindigo, anthraquinone, dioxazine, quinophthalone, and diketopyrrolopyrrole series, and laked colorants such as Ca, Mg, and Al lakes of sulfur- or carboxyl-containing colorants.
Especially preferred organic pigments are polycyclic pigments from the group of the optionally halogenated copper phthalocyanine pigments such as, for example, those of Colour Index Pigment Blue 15, 15:1, and 15:3, Pigment Green 7 and Pigment Green 36, and of the anthraquinone pigments, particularly from the series of the heterocyclic and polycarbocyclic anthraquinone pigments.
Also preferred are metal salts of sulfo- and/or carboxyl-containing monoazo pigments such as xcex2-naphthol pigments, naphthol-AS pigments, and naphthalenesulfonic acid pigments, or 2-hydroxy-3-naphthalene-sulfonic acid, which also come within the term xe2x80x9claked azo pigmentsxe2x80x9d.
Inorganic fillers are equally considered pigments for the purposes of the present application.
Examples of inorganic fillers that may be mentioned are calcium carbonate, talc, mica, and barium sulfate.
Suitable compounds from the group of the polyether polyols are preferably homopolymers, copolymers, or block copolymers of ethylene oxide and/or propylene oxide, which are preferably prepared by reacting ethylene oxide and/or propylene oxide with water or with low-molecular-weight alcohols having at least two hydroxyl groups, such as, for example, ethylene glycol, propylene glycol, 1,2- or 1,3-propanediol, 1,2- or 1,4-butanediol, hexanediol, glycerol, or pentaerythritol, or with low-molecular weight amines that carry at least two amino groups with reactive hydrogen atoms, such as ethylenediamine. Preferred polyether polyols are polyalkylene glycols that have a mean numeric average molecular weight of 200 to 11,000, in particular 250 to 4000, especially preferably 250 to 1000 g/mol. Very especially preferred are polyethylene glycols and/or polypropylene glycols inclusive of tripropylene glycol.
Other preferred polyether polyols are block copolymers that are obtained by subjecting ethylene oxide and/or propylene oxide onto bifunctional alcohols or amines to a controlled, continuous polyaddition reaction, particularly block copolymers of the abovementioned type that are soluble in or miscible with water, such as those known under the names Pluronic(copyright) or Tetronic(copyright).
Suitable compounds from the group of the reaction products of alkylene oxides with alkylatable compounds are, in particular, surfactants based on fatty alcohols, fatty amines, fatty acids, phenols, alkyl phenols, carboxamides, and resin acids. They are, particularly, for example, ethylene oxide adducts from the class of the reaction products of ethylene oxide with
(m) saturated and/or unsaturated fatty alcohols having 6 to 25 carbon atoms or
(n) alkylphenols having 4 to 12 carbon atoms in the alkyl radical or
(o) saturated and/or unsaturated fatty amides having 14 to 20 carbon atoms or
(p) saturated and/or unsaturated fatty acids having 14 to 22 carbon atoms or
(q) hydrogenated and/or unhydrogenated resin acids,
(r) esterification and/or arylation products that have been produced from natural or modified, optionally hydrogenated, fatty substances from castor oil and that are optionally linked to give repeat units by esterification with dicarboxylic acid.
Preferred as component (b) are compounds from classes (m), (o) and (p), particularly ethylene oxide adducts of optionally hydrogenated castor oil with 10 to 100 molar units (preferably 15 to 80 molar units) of ethylene oxide.
Compounds from the group of the oxalkylated phenols, particularly in the form of optionally ionically-modified phenol/styrene polyglycol ethers, are disclosed in DE-A 19 644 077.
Phenol/styrene polyglycol ethers that are preferred are those of the formula (X) 
wherein
R15 is hydrogen or C1-C4-alkyl,
R16 is halogen or CH3,
R17 is hydrogen, C1-C4-alkyl, C1-C4-alkoxy, C1-C4-alkoxycarbonyl, or phenyl,
m is a number from 1 to 4,
n is a number from 6 to 120, and
R18 is identical or different for each unit indicated by n and represents hydrogen, CH3, or phenyl, with the proviso that if CH3 is present in the various xe2x80x94(xe2x80x94CH2xe2x80x94CH(R18)xe2x80x94Oxe2x80x94)-groups, then R18 represents CH3 in 0 to 60% of the overall value of n and represents hydrogen in 100 to 40% of the overall value of n and, if phenyl is present in the various xe2x80x94(xe2x80x94CH2xe2x80x94CH(R18)xe2x80x94Oxe2x80x94)-groups, then R18 represents phenyl in 0 to 40% of the overall value of n and represents hydrogen in 100 to 60% of the overall value of n.
Preferred ionically modified phenol/styrene polyglycol ethers (X) are those of the formula (XI) 
wherein
R15xe2x80x2, R16xe2x80x2, R17xe2x80x2, R18xe2x80x2, mxe2x80x2 and nxe2x80x2 adopt the scope of definition of R15, R16, R17, R18, m, and n, respectively, but independently thereof,
X represents the group xe2x80x94SO3xe2x88x92, xe2x80x94SO2xe2x88x92, xe2x80x94PO3=, or xe2x80x94COxe2x80x94(R19)xe2x80x94COOxe2x88x92,
Kat represents a cation from the group consisting of H+, Li+, Na+, K+, NH4+, or xe2x80x94HOxe2x80x94CH2CH2xe2x80x94NH4+, with the proviso that if X is xe2x80x94PO3=, then two Kat are present, and
R19 represents a divalent aliphatic or aromatic radical, preferably C1-C4-alkylene (particularly ethylene), C2-C4-monounsaturated radicals (especially acetylene), or optionally substituted phenylene (particularly ortho-phenylene in which possible substituents are preferably C1-C4-alkyl, C1-C4-alkoxy, C1-C4-alkoxycarbonyl, or phenyl).
The pigment preparations used in accordance with the invention may contain, as additional additives, agents conventionally used in pigment preparations, such as preservatives, UV stabilizers, pH regulators, softeners, and other surfactants, such as, for example, wetting or antifoam agents.
Suitable antifoams and foam preventatives are, in particular, products based on natural oils or mineral oils, optionally chemically modified alcohols, and chemically modified silicones.
Suitable water softeners are, for example, medium-to-high molecular weight polyphosphates, such as Calgon(copyright).
In a particular embodiment, the pigment preparations used in accordance with the invention contain, as additional component (c), optionally hydrophobicized highly-disperse amorphous pyrogenic silicas, optionally hydrophobicized ultrafinely divided kaolin, and/or highly dispersed alumina. Preferably, component (c) has a specific surface [B.E.T. method] of 2 to 500 m2/g, preferably 10 to 370 m2/g.
Furthermore, the pigment preparations may additionally contain specific thickeners.
Suitable thickeners that may be mentioned are those from the group of anionic or nonionic organic water-soluble polymers that in the broader sense are also considered protective colloids for the solid pigment preparation. Especially preferred are organic thickeners that preferably have a solubility in water of  greater than 100 g/l.
A compound that is preferably employed as organic thickener is one whose 4% strength by weight aqueous solution has a viscosity of xe2x89xa72 mPaxc2x7s at 20xc2x0 C.
Preferred organic thickeners are compounds selected from the following groups:
Dextrins or cyclodextrins,
Starch and starch derivatives, particularly degraded or partially degraded starch,
Anionic polyhydroxy compounds, particularly xanthan or carboxymethylcellulose,
Cellulose derivatives such as, for example, methyl cellulose, particularly hydroxymethyl, hydroxyethyl, or hydroxypropyl cellulose,
Partially hydrolyzed vinyl acetate polymers, preferably polyvinyl alcohol that are hydrolyzed to over 70% and/or vinyl alcohol copolymers, preferably copolymers of vinyl acetate and alkylvinyl esters that are partially or fully hydrolyzed, and polyvinyl alcohol itself,
Polymers of N-vinylpyrrolidone or copolymers with vinyl esters.
Thickeners that are preferably suitable are starch, derivatized starch, and, in particular, degraded starch.
Degraded starch is obtained, for example, by subjecting native potato, wheat, maize, rice, or tapioca starch to oxidative, thermal, enzymatic, or hydrolytic degradation. Preferred in this context are oxidatively degraded starches, especially preferably potato starch that has been oxidatively degraded with hypochlorite.
Other suitable materials are, in particular, dextrins and cyclodextrins. Dextrins that are preferably used are white dextrins, yellow dextrins, and maltodextrins having a solubility in cold water of greater than 50% by weight (preferably greater than 90%) measured at 10 g per 200 ml of water at 20xc2x0 C.
Preferred cyclodextrins are those of the xcex1-CD type with 6 gluco-pyranose units, of the xcex2-CD type with 7 glucopyranose units, and of the xcex3-CD type with 8 glucopyranose units, as well as branched AB, AC, AD-diclosyl-CD type, and mixtures thereof.
Preferred suitable anionic polyhydroxy compounds are poly-saccharides, particularly xanthan, and carboxymethylcellulose.
Cellulose derivatives that can be employed as thickeners are preferably methylcellulose, hydroxymethylcellulose, and hydroxyethyl- and -propylcellulose.
Materials that are particularly suitable as thickeners are at least partially hydrolyzed polymers and copolymers of vinyl acetate that are fully dispersible, preferably fully soluble, in water. Preferred are hydrolyzed polymers and copolymers of vinyl acetate with a degree of hydrolysis of 70 to 97% (preferably 80 to 92%), a molecular weight (Mw) of 1000 to 150,000 g/mol (preferably 2000 to 100,000 g/mol), or a flow viscosity (in accordance with DIN 53 015) of a 4% strength by weight aqueous solution at 20xc2x0 C. of 2 to 35 mPaxc2x7s (preferably 2 to 10 mPaxc2x7s). Flow viscosity is xe2x80x9cHxc3x6pplerxe2x80x9d viscosity measured in accordance with DIN 53 015 as a 4% strength by weight solution at 20xc2x0 C., using a falling-bowl viscometer.
Especially preferred are partially hydrolyzed polyvinyl alcohols, and polyvinyl alcohol itself.
Copolymers of vinyl acetate are taken to mean, as thickeners, preferably fully or partially hydrolyzed vinyl alcohol copolymers, particularly fully hydrolyzed copolymers of alkylvinyl esters and vinyl acetate having an alkylvinyl ester content of preferably 5 to 20 mol %, very especially copolymers of alkylvinyl acetate and vinyl acetate.
Other materials that are suitable as thickeners are homo- and copolymers of N-vinylpyrrolidone that disperse fully in water.
Advantageous thickeners are polymers that contain 35 to 100 mol % of repeat units of the general formula 
wherein R and Rxe2x80x2 are independently of one another H, methyl, or ethyl, and 0 to 65 mol % of one or more monoethylenically unsaturated comonomers, particularly vinyl esters such as vinyl acetate, acrylic esters such as ethyl acrylate, methacrylic esters such as methyl methacrylate, vinylalkyl esters such as vinyl cyclohexyl ether, vinyl halides such as vinyl chloride, vinylcaprolactam, vinylimidazol, allyl alcohol, acrylonitrile, styrene, vinylcarbazol, and others. If appropriate, the copolymers can be ionically modified (cationically or anionically).
The molecular weight (Mw) of the homo- and copolymers of N-vinylpyrrolidone ranges from 2000 to 1,200,000, preferably 10,000 to 150,000 g/mol.
Very especially preferred are homopolymers of N-vinylpyrrolidone, as well as copolymers with vinyl esters and Na methacrylate.
Based on preparations, the solid pigment preparations to be preferably used in accordance with the invention comprise
(a) 30 to 99% by weight (preferably 60 to 95% by weight) of component (a) and
(b) 1 to 100% by weight (preferably 5 to 60% by weight) of component (b) based on the pigment of component (a),
wherein the solid pigment preparations have a water content of less than 10% by weight (preferably less than 3% by weight) and a mean particle size (ex mass distribution) of 20 to 2000 xcexcm (preferably 50 to 1000 xcexcm, particularly 80 to 500 xcexcm).
The solid pigment preparations to be used in accordance with the invention can be prepared, for example, in such a manner that the inorganic or organic pigments or fillers of component (a) in solid form, preferably as finished or unfinished powders, granules, or water-moist filter cakes, are subjected to wet comminution in an aqueous or aqueous-organic medium together with at least some of component (b) and, if appropriate, component (c) and, if appropriate, other additives and the product is subsequently dried.
It is preferred to use in this context an aqueous medium that has a pH of 2 to 12, particularly 2 to 10. In general, a temperature of 0 to 95xc2x0 C. (preferably 20 to 60xc2x0 C.) is applied for the continuous or batchwise wet comminution. Wet comminution is to be understood as meaning, in the present context, homogenizing, grinding, or kneading. This process step converts pigments and/or fillers into a finely-divided state. If appropriate, the additives required can be added before, during, or after generating the finely-divided state. The choice of the methods for achieving the desired finely-divided state prior to drying depends on the aggregation or agglomeration state of the solids employed and on the required expenditure of energy for achieving the desired finely-divided state. Examples of methods that are suitable for organic and inorganic fillers and inorganic pigments are dissolvers, Ultraturrax or rotor-stator mills. Pigments that are aggregated to a greater degree, due to their preparation, suggest, for example, that finely-divided organic pigments, carbon black, and specific finely-divided inorganic oxide pigments can additionally require wet-grinding techniques with a higher specific energy input. This is provided, for example, by stirred-bowl mills and bead mills, dispersion kneaders, roller mills, or high-pressure homogenizers. If appropriate, the resulting aqueous pigment suspensions are subsequently brought to the consistency and composition desired for the subsequent drying step, using either more water or aqueous-organic medium or, if appropriate, other abovementioned additives.
Thereafter, the aqueous suspension is preferably converted into the solid pigment preparation by drying. A suitable method for drying is, in particular, spray drying, especially single-material spray drying using high-pressure nozzles or spiral chamber nozzles, or plate spray drying, freeze-drying with upstream or downstream granulation, or spray-freeze drying, build-up granulation, for example by the plate or drum granulation process, optionally with partially predried product, fluidized-bed drying and granulation, mixer agglomeration, and mixer drying, if appropriate in combination with fluidized-bed or fluid-bed drying. Methods such as mix-agglomeration in suspension, if appropriate with downstream fluidized-bed or fluid-bed drying, granulation by means of paste-forming with downstream after drying, and comminution or pelleting and steam-jet agglomeration, are also suitable. Combinations of the abovementioned processes are also possible.
Especially preferred are the processes of spray-drying by means of high-pressure or spiral chamber nozzles, spray-drying with integrated or downstream fluidized-bed agglomeration and/or drying, build-up granulation by the plate process, or fluidized-bed granulation and drying.
The solid pigment preparations prepared by these processes have, in particular, a water content of less than 10% by weight (preferably less than 3% by weight) and a mean particle size of 20 to 2000 xcexcm (preferably 50 to 1000 xcexcm and in particular 80 to 500 xcexcm). The solid pigment preparations are based in particular on a spherical or sphere-like particle structure.
Due to their composition and good redispersibility, the solid pigment preparations described above are particularly suitable for coloring seed and water-based seed-dressing products and yield the highest possible color or pigment yield. Due to the high pure pigment contents of preferably over 60% by weight, deeper colors can be obtained without undesired dilution of the seed-dressing products by added water, in contrast to pigementations with aqueous fluid preparations with lower pigment concentrations. In contrast to pigment powders also employed in practice, the solid pigment preparations to be used in accordance with the invention are dust-free, outstandingly flowable, readily meterable, and markedly stronger in color, based on the pure pigment content.
The use of the solid pigment preparations for coloring seed or seed-dressing materials can be effected in any desired manner, for example by mixing the solid pigment preparation with water, if appropriate, simultaneously or in succession with pesticides and optionally other additives, and stirring the resulting slurry treatment materials with the seed in suitable apparatuses.
Suitable pesticides which may be mentioned are, for example, the compounds mentioned in WO-A 95 31 889 (page 3, line 13 to page 6, line 13), which are also considered part of the present application.